The invention relates to a piston for an internal combustion engine and to a method for its production.
The piston pin connects the piston with the crankshaft of the internal combustion engine by way of a connecting rod. The piston pin is mounted in pin bores made in pin bosses, and can bend as a result of the tremendous forces that act on the piston during the oscillating movement of the piston. The pin bosses are among the parts of a piston that are subject to the greatest stress. Under great piston stresses, there is the risk of crack formation at the pin bores. Therefore, ways are being sought to relieve stress on the pin bores, particularly in light-metal pistons. This is done, for example, by means of local geometric changes in the usually cylindrical pin bore, which reduce the stress triggered by the deformation of the piston pin. Such geometric changes can be, for example, stress relief pockets, oval pin bores, or conical or spherical bores adapted to the bending line of the piston pin (with regard to the latter see, for example, WO 96/07841 A1). Such geometric changes have been produced by means of complicated precision machining of the pin bore until now.
Pistons having pin bores with slide bearing surfaces are known from German patent application 10 2004 059 392.9. The slide bearing surfaces are coated with a self-lubricating coating made of a resin with solid lubricant particles embedded in it.